U.S. patent number 5,527,931 [Application Number 08/266,116] was granted by the patent office on 1996-06-18 for aqueous dispersable oil and water repellent silane masonry penetrants.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to Larry D. Rich, James F. Sanders.
United States Patent |
5,527,931 |
Rich , et al. |
June 18, 1996 |
**Please see images for:
( Certificate of Correction ) ** |
Aqueous dispersable oil and water repellent silane masonry
penetrants
Abstract
The present invention relates to organosilane compounds used for
treating porous substrates to render them repellent to water-based
and oil-based challenges and to enhance the cleanibility of the
protected surfaces from such challenges.
Inventors: |
Rich; Larry D. (Oakdale,
MN), Sanders; James F. (St. Joseph Township, St. Croix
County, WI) |
Assignee: |
Minnesota Mining and Manufacturing
Company (St. Paul, MN)
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Family
ID: |
25318797 |
Appl.
No.: |
08/266,116 |
Filed: |
June 27, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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854480 |
Mar 20, 1992 |
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Current U.S.
Class: |
556/413; 556/418;
556/419 |
Current CPC
Class: |
C04B
41/4922 (20130101); C09D 4/00 (20130101); C09D
183/08 (20130101); C04B 41/4922 (20130101); C04B
41/4554 (20130101); C04B 41/463 (20130101); C04B
41/502 (20130101); C09D 4/00 (20130101); C08F
230/00 (20130101); C04B 2111/203 (20130101) |
Current International
Class: |
C04B
41/49 (20060101); C04B 41/45 (20060101); C09D
183/08 (20060101); C09D 4/00 (20060101); C07F
007/10 () |
Field of
Search: |
;556/413,418,419 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2125609 |
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Jun 1993 |
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FR |
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2313987 |
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Jul 1994 |
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FR |
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59-140280 |
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Apr 1993 |
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JP |
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Other References
Chemical Abstracts, vol. 102, No. 16, 1985, abstract No. 136805y,
"Surface Treatment Agents", p. 304. .
Rapra Abstracts, vol. 10, No. 9, 26-Feb.-1973, abstract 11068L,
"Fluorosiloxane Copolymers as Soil Release Agents"..
|
Primary Examiner: Shaver; Paul F.
Attorney, Agent or Firm: Griswold; Gary L. Kirn; Walter N.
Sprague; Robert W.
Parent Case Text
This is a continuation of application No. 07/854,480 filed Mar. 20,
1992.
Claims
We claim:
1. An organosilane compound comprising the formula:
where:
R.sub.1 is a group containing at least one hydrophilic
functionality;
R.sub.2 is a group containing at least one hydrophobic
functionality;
R.sub.3 is a group containing at least one oleophobic
functionality;
R.sub.4 is a group containing at least one hydrophilic
functionality;
R.sub.5 is a group containing at least one hydrophobic
functionality;
R.sub.6 is a group containing at least one oleophobic
functionality;
X is a connective moiety;
Y is a second connective moiety
Z is H, OH or a moiety hydrolyzable to OH;
m and n are 0, 1, 2, or 3, m+n=3, and n is at least 1;
a is 0, 1, 2, or 3;
b is 0, 1, 2, or 3;
c is 0, 1, 2, or 3;
where m=0, a, b, c,.gtoreq.1
where m.gtoreq.1,
d is 0, 1, 2 . . . ;
e is 0, 1, 2 . . . ;
f is 0, 1, 2 . . . ;
a+b+c+d+e+f.gtoreq.3, where
a+d=1 or more;
b+e=1 or more; and
c+f=1 or more.
2. The compound of claim 1 wherein said X is selected from the
group comprising an aliphatic group containing a multi-ligand
hetero atom, an aliphatic group or an aromatic group.
3. The compound of claim 1 wherein said are selected from
hydrophobic groups containing aliphatic or an aromatic group.
4. The compound of claim 1 wherein said R.sub.1 are selected from a
hydrophilic groups comprising hydrophilic groups containing oxygen,
hydrophilic groups containing sulfur, hydrophilic groups containing
nitrogen and combinations thereof.
5. The compound of claim 1 wherein said R.sub.3 and R.sub.6 are
fluorinated aliphatic groups.
6. The compound of claim 1 wherein said Z is a halogen.
7. The compound of claim 1 wherein said Z is represented by the
formula:
wherein R.sub.9 is selected from the group comprising a hydrogen,
an aliphatic group, a silane or a silicone atom.
8. The compound of claim 1 wherein said Y is selected from a group
comprising an oxygen or a siloxane, said siloxane comprising:
where q is 1, 2, . . . , and wherein said R.sub.7 and R.sub.8 are
selected from a group comprising a lower alkyl, fluorinated lower
alkyl or aromatic group.
9. The compound of claim 2 wherein said X comprises at least one
nitrogen containing aliphatic group.
10. The compound of claim 1 wherein said compound is derived from a
mixture of reactive precursors.
11. The compound of claim 1 wherein said compound is derived from
independently applied precursors.
12. An aqueous dispersion for treating porous substrates to repel
water and oil based challenges and to provide oil cleanability
comprising:
a. an organosilane comprising the formula:
where:
R.sub.1 is a group containing at least one hydrophilic
functionality;
R.sub.2 is a group containing at least one hydrophobic
functionality;
R.sub.3 is a group containing at least one oleophobic
functionality;
R.sub.4 is a group containing at least one hydrophilic
functionality;
R.sub.5 is a group containing at least one hydrophobic
functionality;
R.sub.6 is a group containing at least one oleophobic
functionality;
X is a connective moiety;
Y is a second connective moiety
Z is H, OH or a moiety hydrolyzable to OH;
m and n are 0, 1, 2, or 3, m+n=3, and n is at least 1;
a is 0, 1, 2, or 3;
b is 0, 1, 2, or 3;
c is 0, 1, 2, or 3;
where m=0, a, b, c,.gtoreq.1
where m.gtoreq.1,
d is 0, 1, 2 . . .
e is 0, 1, 2 . . .
f is 0, 1, 2 . . .
a+b+c+d+e+f.gtoreq.3, where
a+d=1 or more;
b+e=1 or more;
c+f=1 or more; and
b. water.
13. The dispersion of claim 12 wherein said X is selected from the
group comprising an aliphatic group containing a multi-ligand
hetero atom, an al or an aromatic group.
14. The dispersion of claim 12 wherein said are selected from
hydrophobic groups containing an aliphatic or an aromatic
group.
15. The dispersion of claim 12 wherein said R.sub.1 an are selected
from a hydrophilic groups comprising hydrophilic groups containing
oxygen, hydrophilic groups containing sulfur, hydrophilic groups
containing nitrogen and combinations thereof.
16. The dispersion of claim 12 wherein said R.sub.3 and R.sub.6 are
fluorinated aliphatic groups.
17. The dispersion of claim 12 wherein said Z is a halogen.
18. The dispersion of claim 12 wherein said Z is represented by the
formula:
wherein R.sub.9 is selected from the group comprising a hydrogen,
an aliphatic group, a silane or a silicone atom.
19. The dispersion of claim 12 wherein said Y is selected from a
group comprising an oxygen or a siloxane, said siloxane
comprising:
where q is 1,2, . . . , and wherein said R.sub.7 and R.sub.8 are
selected from a group comprising a lower alkyl, fluorinated lower
alkyl or aromatic group.
20. The dispersion of claim 13 wherein said X comprises at least
one nitrogen containing aliphatic group.
21. The dispersion of claim 12 wherein said compound is derived
from a mixture of reactive precursors.
22. The dispersion of claim 12 wherein said compound is derived
from independently applied precursors.
Description
FIELD OF THE INVENTION
The present invention relates to organosilane compounds and more
particularly, to organosilane compounds for treating porous
substrates to render them repellent to water-based and oil-based
challenges and to enhance the cleanability of the protected
surfaces from such challenges.
BACKGROUND OF THE INVENTION
Porous substrates, including concrete, masonry and wood structures,
are vulnerable to the general effects of weathering and
specifically to exposure to water and oil. The weathering of
concrete substantially shortens the useful life of structures such
as highways, bridges, parking ramps and the like. Exposure of wood
and masonry substrates to water and oil can also significantly
shorten the useful life of the product and reduce its aesthetic
appeal even before it is no longer functional. Such substrates are
often sealed with a film-forming resin, such as an epoxy or
urethane product. These coating materials are often quite expensive
and may undesirably alter the appearance of the coated substrate.
Such coatings also seal the product completely, preventing or
greatly reducing the escape of moisture from the coated
substrate.
Silane and siloxane compositions are commercially available to seal
both wood and masonry substrates to provide protection against
water damage, which are typically delivered from volatile organic
solvents. These compositions are undesirable because of the adverse
effects of the solvents upon the atmosphere and the resultant
health problems associated with air pollution. For example,
chlorinated hydrocarbon solvents have been shown to adversely
effect the ozone layer. Other organic solvents such as aromatic
solvents are undesirable because of their toxicity. Therefore,
systems utilizing organic solvents are not desirable.
A number of water-dispersed or water-emulsified silane treatments
have been developed in response to environmental concerns. Examples
of such systems include those described in U.S. Pat. No. 4,648,904
to DePasquale, U.S. Pat. No. 4,517,375 to Schmidt and U.S. Pat. No.
4,661,551 to Mayer et al. DePasquale provides an aqueous emulsion
of a hydrolyzable silane and an emulsifying agent having an
hydrophilic-lipophilic balance (HLB) value from 4 to 15. Schmidt
discloses aqueous impregnation solutions prepared from hydrolyzed
alkyl trialkoxy silanes. Mayer et al. teach the use of a
transparent organosilane composition which is easily dispersed in
water to form a transparent microemulsion.
While providing ecological advantages over solvent-based
treatments, these water-dispersed or water-emulsified silane
materials have not been able to provide performance comparable to
solvent delivered materials. Also, many of these silane/siloxane
materials exhibit poor substrate penetration. Additionally, such
silane materials may not exhibit oil repelling properties.
Silanes which contain fluorine, however, have been used as water
and/or oil repelling agents in other applications such as oil
repellents on automobile and aircraft windshields. For example,
U.S. Pat. No. 3,427,336 to Tiers discloses the use of
perfluorocarbon substituted organosilanes as oil, water and ketone
repellents on glass. Similarly, U.S. Pat. No. 3,442,664 to Heine
discloses an aircraft windshield treatment that contains a low
molecular weight polymeric fluorine-containing organo-siloxane.
Thus, there currently exists a need for compounds which provide a
satisfactory balance of water and oil repellency on porous
substrates. More specifically, there exists a need for compounds
which eliminate the adverse effects associated with solvent based
treatments and which protect porous substrates from water, salt,
waterborne chemicals, and oily stains such as motor oil or paints
and paint films. In addition, there exists a need to apply this
protection from an aqueous delivery system rather than from
solvent.
SUMMARY OF INVENTION
The present invention provides for silane compounds comprising
hydrophilic, hydrophobic, and oleophobic components which can
effectively repel both water and oil based challenges and enhance
the cleanability of a protected substrate. In addition, these
silane compounds eliminate many of the adverse ecological impacts
associated with solvent based systems.
In the treatment composition, these silane compounds preferably are
a condensation product, in part, of distinct moieties having a
hydrophobic, oleophobic and hydrophilic functionalities. The silane
condensation product comprises a three dimensional molecular
network which is derived from reactive precursors either as a
mixture of precursors or as independently applied precursors which
provides protection to a porous substrate and is represented by the
following formula:
where:
R.sub.1 is a group containing at least one hydrophilic
functionality;
R.sub.2 is a group containing at least one hydrophobic
functionality;
R.sub.3 is a group containing at least one oleophobic
functionality;
R.sub.4 is a group containing at least one hydrophilic
functionality;
R.sub.5 is a group containing at least one hydrophobic
functionality;
R.sub.6 is a group containing at least one oleophobic
functionality;
X is a connecting group which preferably contains at least one
nitrogen.
Y is --O-- or (R.sub.7) (R.sub.8) (SiO).sub.q where q is 0, 1, 2 .
. . ;
wherein R.sub.7 and R.sub.8 are selected from a lower alkyl,
fluorinated lower alkyl or aromatic group(s);
Z is H, --OH or a moiety hydrolyzable to --OH;
m and n are 0, 1, 2, 3 and m+n=3;
a is 0, 1, 2, 3;
b is 0, 1, 2, 3;
c is 0, 1, 2, 3;
where m=0, a, b, c,.gtoreq.1;
where m.gtoreq.1,
d is 0, 1, 2 . . . ;
e is 0, 1, 2 . . . ;
f is 0, 1, 2 . . . ;
a+b+c+d+e+f.gtoreq.3, where
a+d=1 or more;
b+e=1 or more; and
c+f=1 or more.
For the purposes of this application, it should be understood that
the groups (R.sub.1 -R.sub.6) can be connected to X through another
R moiety. For example, R.sub.1 can be connected to X indirectly
through R.sub.2.
The present invention also includes delivering the compound as an
aqueous dispersion. If desired, the compound can also be delivered
as a neat material or diluted with a solvent.
The present invention further includes a method of treating the
porous substrate with the compound.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The silane compounds of the present invention are condensation
products of distinct moieties having hydrophobic, oleophobic and
hydrophilic functionalities.
The X moiety is a connective group which provides a means to link
the silicon atom(s) to the hydrophobic, oleophobic and/or
hydrophilic containing groups. This connective group may be an
aliphatic group, an aromatic group or an aliphatic group comprising
a multi-ligand atom. Examples of suitable aliphatic groups include
condensation products of polyols and representative examples of
aromatic groups include phenyl, benzyl, and alkyl benzyl moieties.
Preferably, X comprises one or more nitrogen-containing aliphatic
groups. For example, the nitrogen-containing group can be an amine,
which is linked to the hydrophilic, hydrophobic and/or
oleophobic-containing group(s) by means, for example, of a Michael
addition reaction between the amino nitrogen atom and a reactive
olefinic functionality connected to the hydrophilic, hydrophobic
and/or oleophobic group(s). Alternatively, the linkage between the
nitrogen and the hydrophilic, hydrophobic and/or oleophobic groups
may be achieved by a reaction of the amino nitrogen with an
isocyanate functionality connected to the hydrophilic, hydrophobic
and/or oleophobic groups. In another preferred embodiment, X can
also be a polymeric carbon backbone such as the carbon backbone of
a polyacrylate. It is also contemplated that a hydrophilic,
hydrophobic and/or oleophobic group can be connected through
another oleophobic, hydrophobic or hydrophilic moiety. For example,
the hydrophobic moiety can be connected to X or indirectly through
the hydrophilic moiety.
R.sub.1 and R.sub.4 are groups having hydrophilic properties
comprising functional groups containing heteroatoms such as oxygen,
nitrogen or sulfur. These functional groups typically comprise:
--CO.sub.2 H, --CO.sup.-.sub.2, --SO.sub.3 H, --SO.sup.-.sub.3, or
--OH. Other hydrophilic groups include polyalkylene oxide groups
such as polyethylene oxide, protonated amines and quaternary
compounds. These hydrophilic groups can be introduced into the
silane compound by utilizing a precursor which contains a reactive
olefinic functionality. Examples of suitable monomers include
acrylic acid or other unsaturated carboxylic acids; sulfonated
monomers such as 2-acrylamide-2-methyl propane sulfonic acid and
its salts (commercially available as AMPS from Lubrizol Corp.);
3-sulfopropyl acrylate salts (commercially available from Aldrich
Chem.); and acrylic monomers containing polyalkylene oxide groups
such as polyethylene glycol (400) diacrylate (Sartomer 344
available from Sartomer). Alternatively, the hydrophilic group may
be introduced as an isocyanate functional moiety such as the
reaction product of 1000 molecular weight polyethylene glycol with
toluene diisocyanate to produce a diisocyanate functional
hydrophilic moiety which can be attached in like manner.
R.sub.2 and R.sub.5 are groups containing at least one hydrophobic
functionality and comprise an aromatic or aliphatic moiety.
Representative examples of aromatic moieties include phenyl,
benzyl, and alkyl benzyl moieties. Preferably, the hydrophobic
groups comprise an aliphatic group comprising four or more carbon
atoms. Generally, carbon chains of 50 carbons or less are most
useful although upper limits are set by workable viscosities. By a
workable viscosity, it is understood that the compound or the
dispersion should exhibit a sufficiently low viscosity, so that it
can be coated onto and penetrate into a porous substrate. These
functional groups can be introduced into the compounds of the
invention through the use of precursors such as isooctyl acrylate,
octadecyl acrylate, hexamethylene diisocyanate or higher molecular
weight diisocyanates such as "DDI" 1410, a C.sub.36 diisocyanate
available from Henkel Corp.
R.sub.3 and R.sub.6 are groups containing at least one oleophobic
functionality. Suitable oleophobic compounds include a class of
fluoroaliphatic group represented by the following formula:
R.sub.f is a fluoroaliphatic group which contains from 3 to about
20 carbon atoms, and most preferably from about 6 to about 14
carbon atoms. The perfluorinated group can contain straight chain,
branched chain or cyclic alkylene groups or combinations thereof.
The perfluorinated alkyl group can, optionally, contain catenary
hetero atoms such as oxygen, nitrogen, divalent or hexavalent
sulfur. It is preferred that the perfluorinated alkyl group contain
from about 40% to about 78% fluorine by weight and more preferably
from about 50% to about 78% fluorine by weight. The terminal
portion of the perfluorinated alkyl group should comprise at least
7 fluorine atoms, e.g. CF.sub.3 CF.sub.2 CF.sub.2 --,
(CF.sub.3).sub.2 CF--, --CF.sub.2 SF.sub.5, or the like.
Perfluorinated aliphatic groups (i.e., those of the formula C.sub.n
F.sub.2n+1) are the most preferred embodiments of the
perfluorinated alkyl moieties.
Q is a linking group, or a covalent bond, which provides a means to
link R.sub.f with the connecting group X or a hydrophilic or
hydrophobic group. The linking group Q, can comprise a hetero
atom-containing group, e.g., a group containing --S--, --O--, and
or --NR--, or a combination of such groups, for example, --CO--,
--CONR--, SO.sub.2 --, --SO.sub.2 --N(CH.sub.3)--, --C.sub.3
H.sub.6 Cl--, --CONR--, SO.sub.2 --, --SO.sub.2 N(CH.sub.3)--,
--OC.sub.2 H.sub.4 --, --C.sub.n H.sub.2n -- where n is 1 to 6.
In addition, the perfluorinated alkyl moiety can be connected to X
by using monomers such as ethyl perfluoro octyl sulfonamido ethyl
acrylate prepared as described Example 3 of U.S. Pat. No. 2,803,615
which is herein incorporated by reference except that acrylic acid
was used instead of methacrylic acid. Another useful monomer is the
reaction product of perfluorooctyl sulfonyl fluoride prepared as
described in Example 5 of U.S. Pat. No. 2,732,398, which is herein
incorporated by reference, that can react with an amine functional
connecting group, such as where X equals a primary or secondary
amine. Another way of incorporating the oleophobic group into the
compounds of the invention is to react an isocyanate-functional
fluorine-containing moiety with a connecting group containing a
primary or secondary amine or an alcohol functional group. An
example of this alternative is the reaction of N-ethyl-N-.sub.2
-hydroxyethyl perfluoro octane sulfonamide, the preparation of
which is described in Example 3 of U.S. Pat. No. 2,803,656, with
toluene diisocyanate to form an isocyanate-functional monomer.
Other oleophobic groups suitable for use in the materials of the
present invention include oligomers of tetrafluoroethylene and
hexafluoropropene disclosed in U.S. Pat. No. 2,918,501 incorporated
herein by reference, which through additional chemical reactions,
can be modified to produce silane functional materials.
Z is a hydrogen, hydroxy group or any group readily hydrolyzable to
a hydroxy functionality. For example, Z may be a halogen, or
OR.sub.9 wherein R.sub.9 is hydrogen, a lower aliphatic group,
silane or silicon atom.
Y is a connective group which can comprise an oxygen or a compound
having the formula:
where q is 0, 1, 2, . . . and R.sub.7 and R.sub.8 are hydrogen,
hydroxyl, lower alkyl groups such as methyl, ethyl, propyl and
butyl groups, fluorinated lower alkyl groups or aromatic
groups.
The amounts of the hydrophilic, hydrophobic and oleophobic moieties
depend on the nature of those moieties. For example, sulfonic acid
salts are more hydrophilic than polyethylene glycol moieties and
therefore less sulfonic acid salt will be required than for the
polyethylene glycols. Similarly, methyl groups are less hydrophobic
than octyl groups and therefore substantially more methyl groups
are required to balance the properties.
To maximize the protective and cleanability properties on porous
substrates while maintaining the advantage of an aqueous delivery
system, it is essential that the compound of the present invention
contain at least one hydrophilic, one hydrophobic and one
oleophobic group. While all three groups can be present on one
portion of the molecule (i.e., the connective group X), oil and
water repellency properties can also be achieved with the various
functional groups being distributed over other portions of the
molecule (i.e., attached to the pendent group Y). Additionally, the
presence of two or more functional groups of a particular type does
not adversely impact upon the repellency and cleanability
properties, and is frequently desired, to achieve optimal oil and
water repellency properties.
The organosilane compounds of the present invention can be made in
a variety of ways. However, it is preferred to prepare them through
a Michael addition reaction between an aminoalkyl alkoxy silane and
a reactive olefinic functionality connected to the hydrophilic,
hydrophobic and/or oleophobic groups. If desired, the mixture can
either be further reacted with isocyanates to produce an oligomeric
material having hydrophilic, hydrophobic and oleophobic containing
groups or it can be dispersed in water prior to the oligomerization
process.
The compounds of the present invention can be delivered as a neat
material, diluted with a solvent, or preferably as an aqueous
dispersion. If a solvent(s) is used as a vehicle to deliver the
compounds of the present invention, the solvent(s) can be used
alone or in conjunction with water. Suitable solvents include
alcohols, ketones, esters, hydrocarbons and the like. When used in
conjunction with water, the solvents are preferably water miscible.
If the compounds are delivered as an aqueous dispersion or if they
are diluted with a solvent, the amount of each compound and
delivery vehicle can vary over a broad range and can be selected to
provide the desired protection and cleanability on the treated
porous substrate. In general, it is preferred that the dispersion
should comprise from about 1 to about 40 percent by weight compound
and from about 60 to about 99 percent by weight of the water and
solvent.
Porous substrates are treated with the compounds of the present
invention by applying sufficient amounts of the compounds to the
substrate to produce the desired cleanability and repellency
properties. Preferably, the compounds are applied as a 20% solids
dispersion at a coverage rate of 0.025 l/m.sup.2 (1 gallon per 125
square feet). Once applied, the compounds are allowed to penetrate
the porous substrate. The water or solvent is allowed to evaporate
and the compound is allowed to react, at least in part, on, with,
and/or within the porous substrate.
If desired, distinct precursors having oleophobic functionality,
hydrophobic functionality and the hydrophilic functionality can be
applied to the porous substrate and allowed to condense in situ to
form the compound of the present invention. If condensation is
partial, the compound will necessarily coexist with any unreacted
precursors.
TEST METHODS
Oil Repellency
The oil repellency of treated test cubes is measured by applying a
drop of mineral oil (50-200 centipoise viscosity) and/or motor oil
(S.A.E. 30 weight) to the surface of treated concrete and/or mortar
cubes while measuring the contact angle and observing the beading
or spreading of the drop. The oil drop is allowed to remain on the
masonry surface for 5 minutes, after which it is removed from the
surface by blotting with a paper towel. The surface is subsequently
examined for any indication of staining or discoloration. A scale
of 0-5 is used to provide a subjective rating of the treated cube.
Higher numbers indicate better oil repellency. 0 indicates complete
wetting of the test cube surface and substantial staining or
discoloration and 5 indicates beading of the oil drop and no
significant staining or discoloration. In general, an oil
repellency of 4 or higher is desired.
Oil Cleanability
Oil cleanability is the ability to remove oily stains or
discoloration from a treated masonry surface. It is measured by
placing a masonry test cube which had been previously treated with
a repelling compound and allowed to cure for seven days at ambient
conditions, in approximately 1/8 inch of used diesel oil
(Pennzoil.TM. S.A.E. 30 used for approximately 2000 miles in a
General Motors 5.7 liter V8 diesel engine) for a period of 24
hours. The stained test cube is then cleaned with a commercially
available masonry degreaser (such as Titan-oil Flow, available from
Titan Chem., Inc., Sunnyvale, Calif.) according to the
manufacturer's directions and allowed to dry. Each test cube was
subjected to a series of four staining/degreasing cycles with a
three day drying period between each cycle. The degree of
discolorization is rated on a subjective scale of 0-5. 0 indicates
severe staining and 5 indicates no discoloration. In general, an
oil cleanability rating of 4 or higher is desired.
Water and Salt Barrier Properties
The water and salt barrier properties of treated test cubes are
evaluated according to the test identified as Test NCHRP 244 Test
and described in the National Cooperative Highway Commission
(NCHRP) report #244, Series II, available from the Transportation
Research Board National Academy of Sciences, 2101 Constitution Ave.
N.W., Washington, D.C. 20418. The test provides a relative value of
a treated sample's resistance to water and salt challenges.
The test is conducted by applying a repelling treatment to a test
cube at the manufacturer's recommended rate and allowing the cube
to cure at 24.degree..+-.3.degree. C. (75.degree..+-.5.degree. F.)
and 50.+-.3% relative humidity for seven days. The treated cubes
are then soaked in a 15% (wt/wt.) sodium chloride solution with
periodic weighings.
Performance is calculated utilizing the equation:
where;
.DELTA.test cube=percent weight gain of test cube, and
.DELTA.std. cube=percent weight gain of untreated control cube.
Higher numbers indicate better repellency and represent a treated
cube's reduction in water pickup as compared to uncoated control
cubes. A difference of about 5 percentage points generally
represents a significant performance difference. Generally, a
number of 70 or greater is desired.
Penetration depths are determined by splitting a sealed, cured cube
and measuring the dry edge width after wetting the split face. A
water repellent penetration of 0.16 cm for the cubes described
below is desirable.
Paint Cleanability Properties
Paint cleanability is a measure of the ability of a repelling agent
to protect a surface from paint. The paint cleanability properties
are evaluated by treating test cubes which are partially masked
with 3M Brand Masking Tape are treated with a repelling agent.
Next, Krylon.TM. flat black spray paint is sprayed on the unmasked
portion and allowed to dry for 24 hours. 3M Brand Magic Tape is
then applied to the painted surface and removed with a rapid even
motion. The test cubes are then visually inspected for residual
paint and compared to untreated test cubes tested in the same
manner.
Test Samples
The concrete and mortar cubes (2".times.2".times.2") test samples
were prepared from the mix shown in Table 1:
TABLE 1 ______________________________________ Concrete Mix Mortar
Mix (lbs./yd.sup.3) (% by wt.) Description
______________________________________ Cement 564 1 Regular Type I
Portland Cement (ASTM:C150) Admixture 5.0 oz -- Air-Entraining
Agent, (ASTM:C260) Fine Aggregate 1,210 2.744 Sand, (ASTM:C33)
Coarse Aggregate 1,850 -- Gravel, (3/4"-#4) (ASTM:C33) Water 265
0.547 Water/Cement 0.47 -- Ratio Air Content (calc) 6% --
______________________________________
Once mixed, the test cubes were moisture-cured for 28 days with the
compressive strength of the cubes being monitored at 7 and 28 days.
The measured compressive strength after 7 and 28 days is reported
below in Table 2.
TABLE 2 ______________________________________ Compressive Strength
(psi) Concrete Mix Mortar Mix
______________________________________ 7 Days 3,380 4,060 28 Days
4,580 4,820 ______________________________________
Subsequent to the 28 day cure and prior to being treated with a
sealer, the test cubes were lightly sandblasted to remove loose,
flaky particulate materials.
EXAMPLE 1
Adduct 1
An adduct which was a Michael reaction product of a hydrophobic
group, isooctyl acrylate (IOA), and a connecting group, aminopropyl
triethoxy silane (APS), was prepared by stirring a homogeneous
mixture of IOA (890 gms., 5.2 moles), and APS (1000 gms., 4.5
moles, available from Union Carbide, Danbury, Conn.) at room
temperature for approximately 48 hours.
Adduct 2
An adduct which was a Michael reaction product of a hydrophilic
containing group, polyethylene glycol diacrylate (PEGDA) and a
connecting group, aminopropyl triethoxy silane (APS), was prepared
by stirring a homogeneous mixture of PEGDA (1025 gms., 2.0 moles,
Sartomer 344, available from Sartomer Co., West Chester, Pa.) and
APS (892 gms., 4.03 moles) at room temperature for approximately 48
hours.
Adduct 3
A partial perfluoro sulfonyl ester of the PEGDA/APS Michael
addition product which contained an oleophobic group was prepared
by adding perfluorooctyl sulfonyl chloride, the oleophobic group,
(150 gms., 0.28 mole, prepared according to U.S. Pat. No.
3,427,336) to Adduct 2 (150 gms., 0.16 mole, 0.32 eq.) in isooctyl
trimethoxy silane (300 gms., VP 1316, available from Wacker
Chemical, Adrian, Mich.) under a N.sub.2 atmosphere. The reaction
was cooled in an ice bath and the sulfonyl chloride added over a
period of approximately 10 minutes with vigorous stirring. On
completion of the sulfonyl chloride addition the reaction mixture
was allowed to warm to room temperature and stirred, under a
N.sub.2 atmosphere, for approximately 16 hours.
Premix 1
Adduct 1 (35 gms., 0.09 moles) and Adduct 3 (50 gms.) in isooctyl
trimethoxy silane (50 gms.) were mixed to produce a premix (Premix
1) comprising a mixture of alkoxy silane-functional moieties
containing hydrophilic, hydrophobic and oleophobic functional
groups. Premix 1 was dispersed in water prior to application to
siliceous surfaces. Alternatively, the Premix 1 can be further
reacted to produce an oligomeric material containing hydrophilic,
hydrophobic and oleophobic functional groups.
Adduct 4
An oligomeric silane adduct (Adduct 4) containing hydrophilic,
hydrophobic and oleophobic functional groups lightly cross-linked
by polyurea linkages was prepared by adding hexamethylene
diisocyanate (5.0 gms., 0.03 moles, available from Mobay
Corporation, Pittsburgh, Pa.) to Premix 1 (67.5 gms.) and
vigorously stirring the reaction mixture for 24 hours at ambient
conditions.
Dispersion 1a
Twenty gms. of Premix 1 were added to water (80 gms.) with mild
agitation to produce a dispersion (Dispersion 1a, 20% solids) which
maintained its stability for several hours without additional
agitation. The dispersion was applied to the test cubes at a
coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal) and allowed
to cure at room temperature for approximately seven days, after
which the cubes were evaluated for oil and water repellency
properties as well as cleanability performance. The test results
are reported in Table 3.
Dispersion 1b
Twenty gms. of Adduct 4 were added to water (80 gms.) with mild
agitation to produce an dispersion (Dispersion 1b, 20% solids)
which maintained its stability for several hours without additional
agitation. The dispersion was applied to concrete and mortar test
cubes at a coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal)
and allowed to cure at room temperature for approximately seven
days, after which the cubes were evaluated for oil and water
repellency properties, paint protection and cleanability
performance. The test results are reported in Tables 3 and 4.
EXAMPLE 2
Adduct 5
An adduct which was a Michael addition product of N-ethyl perfluoro
octyl sulfonamide acrylate, the oleophobic containing group
(NEPOSA, available from 3M, St. Paul, Minn. as FX-13) and
aminopropyl triethoxy silane, the connecting group (APS), was
prepared by stirring a homogeneous mixture of NEPOSA (250 gms., 0.4
moles), and APS (88 gms., 0.4 moles) at room temperature for
approximately 48 hours.
Premix 2
A mixture of silane-functional moieties containing hydrophilic,
hydrophobic and oleophobic functional groups consisting of Adduct 5
(35 gms., 0.04 moles), Adduct 1 (50 gms., 0.13 moles) and Adduct 2
(35 gms., 0.05 moles) in isooctyl trimethoxy silane (50 gms.) was
stirred for approximately 3 hours at ambient temperatures to
produce a premix (Premix 2).
Adduct 6
An oligomeric silane adduct (Adduct 6) containing hydrophilic,
hydrophobic and oleophobic functional groups lightly cross-linked
by polyurea linkages was prepared by adding hexamethylene
diisocyanate (5.0 gms., 0.03 moles, available from Mobay
Corporation, Pittsburgh, Pa.) to Premix 2 (77.5 gms.) and
vigorously stirring the reaction mixture for 24 hours at ambient
conditions.
Dispersion 2a
Premix 2 (20.0 gms.) was added to water (80 gms.) with mild
agitation to produce a dispersion (Dispersion 2a) which maintained
its stability for several hours without additional agitation. The
dispersion was applied to concrete and mortar test cubes at a
coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal) and allowed
to cure at room temperature for approximately seven days, after
which the cubes were evaluated for oil and water repellency
properties and cleanability performance. The test results are
reported in Table 3.
Dispersion 2b
Adduct 6 (20 gms.) was added to water (80 gms.) with mild agitation
to produce a dispersion which maintained its stability for several
hours without additional agitation. The dispersion was applied to
concrete and mortar test cubes at a coverage rate of 0.025 m.sup.2
/l (125 ft.sup.2 /gal) and allowed to cure at room temperature for
approximately seven days, after which the cubes were evaluated for
oil and water repellency properties and cleanability performance.
The test results are reported in Table 3.
Comparative Example 1
This example examined the ability of the individual adducts of
Example 2, when used independently or in combination with just one
other adduct, to produce oil and water repellency properties and to
provide adequate cleanability performance.
Comparative Example 1a
Adduct 5 (20 gms.) was diluted with ethyl alcohol (80 gms.), the
resulting solution applied to concrete and mortar cubes at a
coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal) and allowed
to cure at room temperature for approximately seven days, after
which the cubes were evaluated for oil and water repellency
properties and cleanability performance as previously
described.
The compound which contained only oleophobic groups, displayed some
oil repellency properties, but showed minimal water barrier
properties and poor cleanability.
Comparative Example 1b
A premix (Premix 3) containing a mixture of silane or alkoxy silane
functional moieties having hydrophobic and oleophobic functional
groups consisting of Adduct 5 (35 gms., 0.047 moles), Adduct 1 (50
gms., 0.13 moles) and isooctyl trimethoxy silane (50 gms.) was
prepared by stirring the mixture for approximately 3 hours at
ambient temperatures. A dispersion could not be prepared from this
premix because it lacked a hydrophilic functional group, so 20 gms.
of the premix was diluted with ethyl alcohol, the solution applied
to concrete cubes at a coverage rate of 0.025 m.sup.2 /l (125
ft.sup.2 /gal) and allowed to cure at room temperature for
approximately seven days, after which the cubes were evaluated for
oil and water repellency properties and cleanability performance as
previously described. Treated samples failed the cleanability
test.
Comparative Example 1c
A premix (Premix 4) containing a mixture of silane or alkoxy silane
functional moieties having hydrophilic and oleophobic functional
groups consisting of Adduct 2 (25 gms.) and Adduct 3 (25 gms.) was
prepared by stirring the mixture for approximately 3 hours at
ambient temperatures. Twenty grams of the resulting premix were
added to water (80 gms.) with vigorous agitation to produce a
dispersion (20% solids) which was applied to concrete cubes at a
coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal). The cubes
were evaluated for oil and water repellency properties and
cleanability performance after curing at room temperature for
approximately seven days. The water repellency properties were low
for the test cubes.
Comparative Example 1d
A premix (Premix 5) containing a mixture of alkoxy silane
functional moieties having hydrophilic and oleophobic functional
groups consisting of Adduct 2 (25 gms.) and Adduct 5 (25 gms.) was
prepared by stirring the mixture for approximately 3 hours at
ambient temperatures and tested as described in Example 1c. The
water repellency properties were low for the test cubes.
Comparative Example 1e
A conventional silane treatment composition which contained
hydrophobic functional groups was prepared in the following manner.
A 20% solids solution of isooctyl trimethoxy silane in mineral
spirits was applied to concrete and mortar test cubes at a coverage
rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal) and allowed to cure at
room temperature for approximately seven days, after which the
cubes were evaluated for oil and water repellency properties, paint
protection and cleanability performance. The test results reported
in Tables 3 and 4 indicate that the oil repellency, paint
protection and cleanability are unsatisfactory.
EXAMPLE 3
A silane terpolymer containing hydrophilic, hydrophobic and
oleophobic functional groups was prepared by the free radical
polymerization of acrylic acid, trimethoxysilylpropyl methacrylate,
2-methyl hexyl methacrylate, and N-ethyl perfluorooctyl sulfonamide
acrylate. Thus, a mixture of toluene (30 gms.), isopropanol (30
gms.), mercapto acetic acid (1.5 gms.), azobisisobutyronitrile (0.6
gms.), acrylic acid (5.0 gms. 0.07 moles), trimethoxysilylpropyl
methacrylate (10.0 gms., 0.04 moles), 2-ethylhexyl methacrylate
(25.0 gms., 0.14 moles, available from Aldrich Chemical Co.), and
N-ethyl perfluorooctyl sulfonamide acrylate (5.0 gms., 0.01 moles)
was heated at 60.degree. C. (140.degree. F.), with stirring and
under a N.sub.2 atmosphere, for approximately 16 hours. Solvents
were removed from the reaction mixture using a rotary evaporator
(Buchi, Model 121) and water aspirator vacuum to produce a viscous
polymer oil. A stable dispersion of the polymer was prepared by
mixing a portion of the terpolymer (10 gms.) with isooctyl
trimethoxy silane (10 gms.) and adding the resulting mixture to
water (79 gms.) containing NaOH (1.0 gm.) with vigorous agitation.
The dispersion was applied to concrete and mortar test cubes at a
coverage rate of 0.025 m.sup.2 /l (125 ft.sup.2 /gal) and allowed
to cure at room temperature for approximately seven days, after
which the cubes were evaluated for oil and water repellency
properties and cleanability performance. The test results are
reported in Table 3.
Comparative Example 2
A sample of a silane compound which contained hydrophobic and
hydrophilic functional groups was prepared in the following manner.
A mixture of alkoxy silane functional moieties containing
hydrophilic, and hydrophobic functional groups consisting of Adduct
1 (35 gms., 0.09 moles) and Adduct 2 (50 gms., 0.05 moles) in
isooctyl trimethoxy silane (50 gms.) was stirred the under a
N.sub.2 atmosphere for approximately 12 hours at ambient
temperatures. The resulting mixture was oligomerized by adding
hexamethylene diisocyanate (5.0 gms., 0.03 moles) to the adduct and
vigorously stirring the reaction mixture for hours at ambient
conditions to produce an oligomer containing hydrophilic and
hydrophobic functional groups lightly cross-linked by polyurea
linkages.
A portion of the reaction mixture (20 gms.) was then added to water
(80 gms.) along with agitation of sufficient intensity to produce a
dispersion (20% solids) which maintained its stability for several
hours without additional agitation. The dispersion was applied to
concrete and mortar test cubes at a coverage rate of 0.025 m.sup.2
/l (125 ft.sup.2 /gal) and allowed to cure at room temperature for
approximately seven days, after which the cubes were evaluated for
oil and water repellency properties and cleanability
performance.
TABLE 3 ______________________________________ Water Repellency
Days Immersed Oil Cleanibil- Example 1 3 7 14 21 Repellency ity
______________________________________ 1a 93 83 80 70 62 5 4 1b 96
94 88 82 78 5 5 2a 90 83 80 74 68 4 4 2b 94 89 84 77 72 5 5 3 94 90
85 79 76 5 5 Comp. 1e 94 91 86 80 75 0 0 Comp. 2 93 86 82 79 76 0 2
______________________________________
TABLE 4 ______________________________________ Example Paint
Cleanability ______________________________________ 1b Residual
paint deep in sample pores Comp. 1e No paint removed Untreated No
paint removed Sample ______________________________________
In general, cubes treated with the compounds of the present
invention performed better than those not treated. Cubes treated
with the compounds of the present invention exhibited good
repellency properties, paint protection and oil and paint
cleanability for both waterbased and oilbased challenges. Exclusion
of hydrophobic moieties lowered the water repellency properties of
treated cubes. Similarly, the exclusion of oleophobic moieties
decreased the oil repellency properties of the treated cubes to 0.
Moreover, compounds lacking hydrophilic and oleophobic functional
groups did not protect treated substrates from paint
challenges.
In summary, novel organosilane compounds which are capable of
imparting repellent properties as well as enhancing cleanability
properties of porous substrates have been described. Although
specific embodiments and examples have been disclosed herein, it
should be borne in mind that these have been provided by way of
explanation and illustration and the present invention is not
limited thereby. Certainly modifications which are within the
ordinary skill in the art are considered to lie within the scope of
this invention as defined by the following claims including all
equivalents.
* * * * *